Electric heater



Nov. 7, 1950 o. L. DILWORTH 2,528,503

ELECTRIC HEATER Filed Sept. 21, 1945 INVEN TOR. 0770.11. D/L WORTH.

BY p46; Z/Zu' HTTORNEY.

Patented Nov. 7, 1950 UNITED STATES PATENT OFFlCE- ELECTRIC HEATER OttoL. Dilworth, Hartford, Conn.

Application September 21, 1945, Serial N 0. 617,750

3 Claims. 1

This invention relates to electric heaters and has for an object thereofthe provision of an electric heating element which is adapted to producea maximum degree of heating in proportion to its size and with a minimumamount of current consumption.

A further object of the invention is to provide a novel heating elementadapted for utilizing the effects of radiation to increase the heatingcapacity of the element.

Further objects and advantages of my invention will be more clearlyunderstood from the following description and from the accompanyingdrawings in which:

Fig. 1 is a side view, partly in central vertical section, of anelectric stove embodying m invention.

Fig. 2 is a bottom view thereof on line 22 of Fig. 1.

Fig. 3 is an enlarged view showing the arrangesection, of the oxygenconsumer.

Fig. 6 is a plan view of my improved stove with the upper cover andplate removed.

Fig. 7 is a fragmentary side view, in central vertical section, of aninsulated connector used in my improved stove.

As illustrated in the drawings, my improved stove may comprise a casingconstructed of a base upon which is supported a frame 6 that is enclosedwithin an inner shell 1 having integrally therewith a top 8 and aplurality of lateral fins 9, preferably surrounded by a screen orperforated shell ID. If desired, the top 8 may extend over saidperforated shell to retain it in position upon the base 5.

The said stove may be supported upon a suitable stand comprising legs l3which may be secured within a base ring M as shown.

My invention also includes a novel heating element, preferably in theform of a coil [5, which is wound upon suitable refractory spools l6 andI! that are supported in the frame 6 by means of bolts l8 extendingtherethrough. At one side of each of said spools, I provide a copperdisc I9 for the purpose hereinafter set forth.

One end of the said heating element is electrically connected to a setof binding posts 20 mounted on a conductor bar 20-a and the other end ofthe element is connected to a set of similar posts 2| mounted on theconductor bar 2 I-a. The said posts are each mounted on an insulatedconnector having a binding post 22 that extends through the base 5 andis constructed as shown in Fig. 7, wherein the base 5 has a dependingflange 23 through which extends the post 22 that is insulated from thebase by means of a resilient insulating material, such as asbestos orglass fiber, shown at 24 and which is compressed by means of a washer26. The opening in the base is sealed by said asbestos and also by asuitable insulating washer 21 upon which is mounted a spacer 28 thatsupports the conductor bar a or 2 a.

As illustrated, the ends of the resistance Wires in the heating elementcoil [5 are connected to the binding posts 20 and 2| and an electricsupply cord 29 is connected with one Wire 30 extending to the bindingpost 2| and the other wire 30a extending to the conductor bar 2I-athrough a suitable heat responsive control, such as a thermostat 3|,which may be. of a well known construction and which is responsive toheat in the stove for controlling the electrical circuit for theoperation of the heating element. The said thermostat 31 may beadjusted, by means of a knob 33, for the amount of heat desired and mayalso be adjustably positioned nearer to or farther from the base 5 sothat the responsiveness of the thermostat to the heat from the stove maybe selectively changed to further regulate the operation of the heatingelement for the amount of heat desired.

As shown, the thermostat 3| may be carried by a lever 34 which ispivoted at 35 and may be swung on said pivot and then looked in thedesired position by suitable means, such as a nut 36, to retain thethermostat in the desired adjusted position which may be indicated bygraduations 31, preferably on the base 5, registering with a pointer ona dial plate 38 that is carried by the thermostat 3| and has graduationsregistering with a pointer on the knob 33. It is pointed out that whenthe said thermostat is positioned further away from the base 5, it willbe less responsive to theheat from the stove and therefore will permitthe stove to operate at a higher heat than when the said thermostat islocated closer to the base.

An important element of my invention is the novel means which I haveprovided for increasing the heating capacity of the heating element coili5. This is accomplished by uniting a plurality of individual strands ofwire 39, or ribbon, by

plaiting or braiding them together, as shown in Fig. 3 or otherwise, sothat they will form a single resistance wire having a plurality ofindividual strands which are in close proximity with each other and incontact at spaced points. The resistanc wire or plait formed by the saidstrands is then wound into a spiral soil which is in turn wound upon thesupporting spools l6 and ii as shown. After the element is soconstructed, it will comprise a coil, as shown in Fig. 4, within whicheach turn, or loop, will include separate strands that are boundtogether in close proximity but in contact with each other only atspaced points.

In the operation of my invention, the electric current is suppliedthrough the conductor 30 of the cord 29 to the heating element and fromsaid heating element, through the conductor 3l-a. and the thermostat 3|to the other wire 30a of the said cord.

The efficiency of the heating element is greatly increased by theprovision of the multi-strand wire since, when the said heating elementis energized and heated, there is caused a compounded radiation which isdue to the proximity of the individual strands 39 that is maintained bythe spaced points of contact between said strands and which serves tocreate additional heating of the resistance wire as has been proven bynumerous tests and experiments that have been carried out.-

It is commonly known that when a wire is energized it becomesheated andtherefore it radiates heat. The hotter the wire, the more heat itradiates. It isalso known that when a plurality of heated wires areplaced near each other, each tends to-heat the other by radiation.Therefore, by plaiting the strands together, as above described, andenergizing them individually and in parallel within the electriccircuit,I provide a single resistance wire in the form of a plait, orbraid, having a plurality of 'strands'retained in proximity toeachother, whereby each strand tends to heat the other by radiation sothat the temperature of each strand-is thereby raised and the heatingelement will give off a maximum amount of heat for any given amount ofelectric current. I

It will be understood, therefore, that by uniting the strands as abovestated, myinvention provides a heating element having a resistancecontaining a plurality of strands each radiating heat upon the other andthereby effectively producing compound'radiation within the resistancewhich will greatly assist in raising the temperature of the heatingelement so that it will produce more heat without additional consumptionof electric energy.

In the structure shown, the shells i and the cover 8 are integrallyconstructed and the said shell is hermetically secured to the base 5, bysoldering or welding, as at 40, so that the chamber within said shell issufficiently air tight to prevent the entry of air into said chamber and4 around the heating element which operates therein.

If desired, the oxygen may be removed from the chamber by bleeding thesaid chamber with an air pump. For this purpose, there is provided ableeding valve 42 which is connected to a nipple 33 to which may beattached a suitable pump. When the air is removed, the valve 42 isclosed.

From the above it will be clearly understood that my invention providesa novel heating ele ment for electric stoves and the like which iscapable of producing an additional amount of heat in proportion to theamount of electric energy consumed and which may be of types other thanthe open resistance type of heating element herein described withoutdeparting from the scope of my invention.

I claim:

1. For an electric heater of the character described, a heating elementcomprising an insulating support, and a resistance including a pluralityofstrands which are plaited together, formed into an elongated coil, andthen said coil wound around said support, with adjacent turns of thecoilspaced from each other, and connected in parallel within an electriccircuitj whereby heating of said strands will cause radiation from eachstrand onto the others and increase the heating efficiency of theelement.

2. For an electric heater,a heating element comprising an insulatingsupport, and a resistance including a plurality of strands which areplaited together, then formed into a coil, and then said coil wound uponsaid support with adjacent turns of the coil spaced from each other.

3. The method of manufacturing an electric heating element whichcomprises the steps of plaiting a plurality of strands, coiling saidplaited strands into an elongated coil to form a resistance for saidelement, and then winding said coil around a support of insulatingmaterial with adjacent turns of the coil spaced from each other.

- OTTO L. DILWORTH.

REFERENCES CITED The following references are of record in the file ofthis patent: I

' UNITED STATES PATENTS Obermaier 1 Sept. 2'7, 1938

